Metal cartridge and method for producing same



April 1952 M. L. A. PAULVE 2,591,286

METAL CARTRIDGE AND METHOD FOR PRODUCING SAME Filed March 18, 1948 V Arry Patented Apr. 1, 1952 UNI T ED STAT ES PATENT METAL CARiTRIDGE AND.METHOD FOR PRODUCING SAME Marcel Luc Amedee Paulv, Parmain, France Application March'lS, 1948, SerialNo. 15,716 In France April 25, 19.47

i Claims.

The present invention relates to improvements in metal cartridges and more particularly sporting cartridges crimped in star formation. These cartridges are closed by gathering in the free .lips of the open end of the case and permit of avoiding the use of a wad.

These cartridges show a small ,gap in the center which is closed by a drop of varnish or of paramn wax. This method is not satisfactory for the .reason that the outer surface of ,the crimped portion shows very close pleats into which the varnish or wax cannot find their way. The natural effect is that the inside of the cartridge is liable to spoil if it is kept for some time in a damp atmosphere .or if it accidentallyhappens to fall into water. This wetness has of course a very bad effect on the ballistic qualities of the cartridge.

It has already been proposed to avoid this difiiculty by soldering -the crimped edges of the middle opening of the cartridge case. Such a soldering is a very diflicult operation particularly when the case is made of aluminium, moreover this closing by solder upsets entirely the ballistic qualities of the cartridge and cannot be done actually in practice. A thin cardboard mica wad etc. may be inserted between the end part of the crimped wall and the car tridge charge, or again a wad similar to the'wad existing in cartridges to be crimped by rolling over the edge of the casing. However a complete watertightness is not possible by using a washer of such a kind. Besides, the use of such a wad eliminates the advantages obtained by the starshaped crimping of the cartridges which were due precisely to the fact of the absence of such a wad.

One object of this invention is to provide a complete watertightness of the cartridge without any change in its ballistic qualities. With this object in view, the invention concerns a method of making a metallic cartridge in which before completion of the last crimping step which is performed by turning over the folds made in .the open end of the case, one inserts in'Lthe middle gap, a small cylindrical piece of some plastic material.

This small plastic cylinder or thread which is given a suitable diameter greater than that of the gap, is compressed to a high extent by the .end edging of the folds when these latter are bent well back towards the center and the plastic material finds its way between the interstitial spaces .leftbetween these folds and .thus provides a thorough watertight closure of 'the cartridge.

According to the invention, the insertion of the plastic material may be carried out in any suitable way and for instance by injecting itin a pasty condition or by inserting the end of 'a' thread of this plastic material into the aforesaid central gap.

The plastic material employed for this closure may consist of natural or synthetic rubber and, generally speaking, may consist of any standard material classified as a plastic showing at the time of fits'ins'ertion in the gap sufiicient plastic quality 'to make the cartridge completely impervous to moisture.

As a matter of fact, the plastic "material introduced in the gap does not prove a hindrance at all to the opening of the cartridge when-itis fired. Moreover the size of this'plastic material is substantially that'of a grain of shot and does not cause any interference in the cone of fire of the shot.

With metal cartridges, crimpedstar-wise and in use today, the =ci imped end is made slightly tapering or bulging or even flat, butits connection with the cylindrical surface-of the car-'- tridges either at a sharp angle or with a slight radius. When such-a cartridge is put in the gun, it may jam the gun. This is particularly following one, this being due "to the convexity of the crimping. The consequence is (with super sensitive priming), that a cartridge may go off in the'gunmagazine and thus cause a-very serious accident indeed.

An object of :the present invention is to avoid any serious inconveniences of this kind and with this aim in view one of its important pointsis the fact that the star-shaped methodof crimping is carried out so that the crimped'end of the cartridge is concave andlinks up with the cylindrical body of the case through a semi-circus lar profile with a comp.aratively large radius, for instance, over twice thethickness of the wall of the case.

This special feature offers the further advantage that when the folds are bent back over the plastic material closing the central small gap, the flexibility of this plastic cannot'cause any partial upsetting of the crimping as might happen if the folding back formed a horizontal plane crime]. a bulged shape.

In the case of metal cartridges with starshaped crimping "it is not feasible to show the number of the shot or the kind of explosive stamp markings on the cylindrical portion of the metallic case. This arrangement proves unsatisfactory when the cases are carried in a cartridge pouch, the rubbing of the cases against each other and against the inside of the pouch quickly erasing these markings so that after a little while the hunter cannot distinguish between the different ammunition in his pouch.

In accordance with a further feature of the present invention, the cylindrical portion of the case shows one or more concave parts formed for instance, by one or more grooves, the bottom of which carries information or markings indicating the explosive charge, the number of the shot and so on. These markings may be either stamped on, or formed by a distinguishing color painted on the bottom of this or these concave portions of the case.

. The present invention also contemplates as a new article of manufacture, metal cartridges with star-shaped crimping improved in accordance with this invention and characterized by the following features:

l. The hole at the center of the crimping is closed by some form of plastic material which is forced into this central hole When crimping the open end of the cartridge.

2. The crimped end is concave and connected to the cylindrical wall of the case by a semicircular surface of comparatively large radius.

3. The cylindrical wall of the case contains one or more concave portions such as grooves, thev bottom of which carries the required markings indicating the explosive charge and the number of the shot used in the cartridge.

The invention also includes the die employed for '-the last crimping operative step of the cartridge during which the plastic material is inserted in the central gap of the crimped end of the cartridge, and the folds formed at the end of the case are bent back over this plastic materia1 so as to compress it and ensure the watertightness. This folding back of the folds being continued towards the center of the. cartridge until the crimped end of the case assumes a concave shape connected to the cylindrical body bya toreshaped surface of comparatively large radius.

In accordance with the invention, the die employed for this last operation is formed by a recessed socket of an inner diameter corresponding to the outer diameter of the cartridge to be crimped' and of which the bottom is convex and made up of a cone connected to the. wall of the socket constituting the die by a tore-shaped surface of comparatively large radius, the die being provided along its axis with a drilled hole through which is inserted the plastic material constituting the closure of the cartridge.

The following disclosure will give a clearer understanding of the present invention with reference to the accompanying drawings which are given as an example only and in which:

Figure l is an axial section of an improved cartridge case according to the invention before the crimping operation. a

Figure 2 is a diagrammatic view partly in section and partly in elevation showing the last crimping operation and the closure of the cartridge. I

Figure 3 is an elevation given partly in section of the crimped cartridge.

Figure 4 is a plan view showing the top of Figure 3.

The case I of the improved metal cartridge according to the invention has annular grooves or flutings 2 obtained by any suitable means and methods, and for instance by working the metal inwards during the manufacture of the case.

The case is then filled in the ordinary way and its open end is folded over and the folds are bent over towards the center so that this end makes an open cone pointed upwards as shown in Figure 2 of the drawings. These crimping operations are quite standard methods and do not belong to the present invention.

After'these initial standard star-shaped crimping operations, the folds 3 of the end of case I. are bent back towards the center by means of a die 4 formed according to the invention by a recessed socket the bottom f which is convex and forms, for instance, a cone the apex angle of which is suitably selected with respect to the degree of concavity that is wanted on the crimped end of the cartridge I. The cone 5 is connected to the inner wall of the socket forming the die 4 by a tore-shaped surface 6 of comparatively large radius 1'.

An axial bore along the axis 1 is provided in the die 4 and permits the introduction of the plastic material 8 employed for closing the cartridge.

Before pressing the die 3 on the cartridge I, a certain amount of the plastic 8 is fed through the hole '5 and cut in this die so as to enter the opening of the upper end of cartridge I. The die 4 then is lowered and'bends back the folds 3 of cartridge I towards the center so that the end of this cartridge is now concave as shown by Figure 3 of the drawings and connected to the cylindrical portion of the cartridge I by av toreshaped surface 9 of radius 1- corresponding to portionafi of the die 4. During this folding back of the folds 3 towards the center, the edge of these folds presses on. the plastic material 8 and compresses it thoroughly. The cross-sectional area of the hole I of the die 4 and consequently that of the plastic thread 8 are selected so as to be greater than the area of the opening of the cartridge after the folds 3 are bent back. This plastic material 8 thus gets into the interstitial spaces of the folds 3 and forms a plug closing the cartridge I in a perfectly watertight manner. The end of the cartridge has however the faculty of opening out freely when the cartridge is fired. This piece of plastic does not interfere in any way with the cone of fire of the shots since it is about the same size as a grain of shot. (See Figure 3.)

The plastic material 3 is of any suitable character and may be formed either by a thermoplastic material or natural or synthetic rubber introduced preferably in a pasty condition, or in the form 'of a thread through the axial hole 1 of the die. The amount of plastic inserted into the cartridge is selected suitably and any convenient means may be utilised for cutting up the thread 8. My experiments have proved that, in the majorityof cases, the mere withdrawal of the cartridge I from inside the die 4 after the crimping step, was suflicient to break off correctly the thread 8, but it is obvious that a cutting blade might be used, working together with the die 4.

In accordance with the invention, the inside of the groove of fluting 2 bears an impression of paint or varnish ID of Whichthe colour ed to agree with a suitable codeand al- 4 he huntsman to appreciate at one glance the -hind of charge, number of the shot, or any other-loading particulars. These impressions of colours of the carriage may be put on either before or after the crimping of the cartridge and it will be noticed from their position at, the bottom fgf the groove 2, that they will notbe erased by cartridges rubbing against each Rother or against the wall of the cartridge-pouches in which they are carried. 1

The present invention is not restricted to the embodiments herein described and shown above,

but covers all those based on the invention as claimed in the accompanying claims.

What I claim is: L

1. In a method for the manufacture of metal cartridges the step consisting in crimping fin starformation the lips of the open end ogthe usual cartridge case, and closing it by folding and gathering the said lips, the step of sealing in a watertight manner the gap formed at said open end upon the execution of the gathering operation, said sealing being operated by the introduction into'said gap of an element of a preferably plastic finaterial, said material passing preferably through the gap and being situated partly outside'and partly inside of the gap and of the cartridge, the further step of turning over the said gathered end in a substantially perpendicular direction with respect to the axis of said case and in subjecting said preferably plastic material in said gap to a high compression during said turnover operation. 1

2. In a method according to claim.,1 the step consisting in forming said plasticv element by means of an injection under pressure of said mater'ial in a pasty state. I

3. In a method according to claim 1 the step consisting in rendering concave the outer surface of the crimped end of the case and connecting said concave part with theffremaining portion of the case by a tore-shaped surface having a radius the length of which is greater than twice the thickness of the walls of said case.

4. In a method for the manufacture of metal cartridges the step consisting in crimping in star-formation the lips of the open end of the usual cartridge case, and closing itby folding and gathering the said lips, the step of sealing in a watertight manner the jgiap formed at said open end upon the execution of the gathering operation, said sealing being operated by the introduction into said gap of an element of a preferably plastic material in the form of a thread which is cut at the suitable :length, the further step of turning over the said gathered end in a substantially perpendicular direction with respect to the axis of said case and in subjecting said preferably plastic material in said gap to a high compression during said turn-over operation.

MARCEL LUC AMEDEE PAULVE'I.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 50.536 Power Oct. 17, 1865 1,125,644 Brewington Jan. 19, 1915 2,336,066 Cadham Dec. 7, 1943 FOREIGN PATENTS Number Country Date 16,922 Great Britain May 11, 1905 202,252 Great Britain Aug. 16, 1923 106,575 Switzerland Sept. 16, 1924 277,762 Great Britain Sept. 26, 1927 544,814 Great Britain Apr. 29, 1942 

